Call it opsophagy, fish epicurism, or outright gourmanderie – whatever your angle, the world’s eating habits are seriously threatening the wild stocks in our oceans. That mighty scombroid, the bluefin tuna, is a case in point: largely thanks to Homo japonicus, this blue and silver gladiator is now, pound for pound, the most expensive fish on the planet (a single carcase having fetched over fifty-five thousand dollars in Tokyo), and its population is down to a mere 10 per cent of what it was in 1970. There is no moratorium in sight, and it’s anyone’s guess what the flesh of the last ever tunny will fetch in the ichthyolatrous Tsukiji market.